Bearing assembly

ABSTRACT

961,522. Gas turbine plant. ROLLS-ROYCE Ltd. April 4, 1963 [Jan. 9, 1963], No. 1087/63. Heading FIG. [Also in Division F2] A bearing assembly comprises an outer race mounted in a first member; an inner race mounted within said outer race and spaced therefrom by balls or rollers; a second member mounted in the inner race, said first and second members being relatively rotatable; first duct means through which lubricant may pass to cool the inner and outer races; second duct means through which lubricant may pass to the balls or rollers to effect lubrication thereof; and means for supplying the first and second duct means with lubricant from a common source. In an embodiment, a gas turbine engine has a shaft 10 having a compressor and turbine, (not shown) mounted thereon and having a shaft 11 concentrically mounted therein. The shaft 11 has a low pressure compressor and a low pressure turbine (not shown) mounted thereon. The shaft 10 is mounted in a ball bearing 13, having races 12 and 15, the outer race 15 of which is mounted within annular members 16, 17, which are secured to each other and to a fixed structure 20. The shaft 11 has a lubricant supply pipe 21 therein which supplies, by means of centrifugal force and a passage 23, a space 22 located between the shafts 10, 11. A sleeve 24, Fig. 3, having a number of angularly spaced apart pockets 25 therein, is mounted within the shaft 10 so that the lubricant can pass from the space 22, through the pockets 25 and drillings 26 to passages 27 which lead to axially-extending grooves 30 which serve to cool the inner race 12. The outer ends of the grooves 30 communicate by means of drillings 32 with annular chambers 33, 34. The annular members 16, 17 have slotted portions 35, 36, Fig. 2, having slots 37 therein so as to meter the flow of lubricant from the drillings 32 to ducts 40 which lead to the ball bearing 13. Lubricant passes from the bearing 13, through ducts 41 and through drillings 42, 43 in the members 16, 17 respectively, and into the chambers 33, 34 respectively, from where it passes directly to a scavenge passage 44 from the chamber 34 and via a passage 45 from the chamber 33. The outer race 15 of the bearing 13 has grooves 47 therein which are supplied with lubricant from a conduit 50 by way of conduits 51-54 so as to cool the outer race. The lubricant is conveyed from the grooves 47 to the scavenge passage 44 via drillings 43a and the chamber 34. The shaft 11 is mounted in a sleeve 56 which constitutes an inner race of ball bearings 57, 58 having outer races 60, 61 mounted in a sleeve 62, the latter being mounted in the shaft 10. The sleeve 62 carries a frusto-conical member 63, Fig. 4, having holes 66 therein and lubricant is passed from the interior of the shaft 11, to the member 63 via drillings 64 in the shaft 11 which communicate with the pipe 21 by means not shown. The member 63 is formed with scoops 65 which direct a portion of the lubricant to the bearings 57, 58, after which the lubricant passes through drillings 74 in the shaft 10 to the chamber 33 and finally via the passage 45 to the scavenge passage 44. Some of the lubricant which has passed through the drillings 64 is centrifuged up the member 63, through the holes 66 and into an annular chamber 70 from where it passes via drillings 71 to groove 72 to cool the outer race 60 and then through grooves 73 to cool the outer race 61. The lubricant then passes in the chamber 33 via drillings 74 in the shaft 10. In a modification, the slotted portions 35, 36 of the members 16, 17 are omitted.

B. DIVER ETL BEARING ASSEMBLY Oct. 4, 1966 5 Sheets-Sheet 1 Filed Dec.23, 1965 A torneys Oct. 4, 1966 B. Dlvl-:R ETAL BEARING ASSEMBLY 3Sheets-Sheet 2 Filed Dec. 23, '1963 Atorneys Oct. 4, 1966 B. DxvER ETAL3,276,827

BEARING ASSEMBLY Filed Dec. 23, 1963 5 Sheets-Sheet 5 A ttorneys UnitedStates Patent O 3,276,827 BEARING ASSEMBLY Bernard Diver and NormanRobert Robinson, Derby, and Wilfred Henry Wilkinson, Turnditch, Derby,England, assignors to Rolls-Royce Limited, Derby, England, a company ofGreat Britain Filed Dec. 23, 1963, Ser. No. 332,804 Claims priority,application Great Britain, Jan. 9, 1963, 1,087/ 63 6 Claims. (Cl.308-187) This invention concerns a bearing assembly.

According to the present invention, there is provided a bearing assemblycomprising an outer race which is mounted in a first member, an innerrace which is mounted concentrically within said outer race and which isspaced therefrom by rolling elements which are in rolling contact withsaid inner and outer races, a second member which is mounted in saidinner race, said first and second members being relatively rotata-ble,first duct means through which lubricant may pass in contact with atleast a substantial proportion of the respective circumferentialsurface(s) of said inner and/or said outer race(s) which is or areradially spaced from said rolling elements, so as to effect cooling ofsaid surface(s), second duct means through which lubricant may pass tothe rolling elements to effect lubrication thereof, and means forsupplying said first and second duct means with lubricant from a commonsource.

The term rolling elements as used in this specification is intended toinclude ball bearings, roller bearings, needle bearings and the like.

Preferably there are common scavenge means to which may pass lubricantwhich has fiowed through said first and second duct means.

Alternatively, at least a portion of the lubricant which has fiowed pastthe said circumferential surface(s) is supplied to the said second ductmeans.

Thus t-he bearing assembly may comprise at least one chamber into whichpasses the lubricant which has fiowed through said first duct means, theor each said chamber having a lubricant duct associated therewith whichconstitutes the said second duct means, the lubricant duct communicatingwith its chamber by way of a flow metering device which meters theamount of lubricant which may pass to the rolling elements. The flowmetering device may, for example, comprise a slotted member.

The said second member is preferably constituted by rotatable shaftingand, in this case, the said first duct means preferably communicateswith the internal surface of the rotatable shafting by way of one ormore lubricant passages, there being means for providing the saidinternal surface with lubricant which, in operation, will becentrifugally forced through said lubricant passage(s) to said firstduct means.

The said internal surface is preferably recessed to form at least onepocket which communicates with a said lubricant passage, the or eachsaid pocket, in operation, directing the lubricant into the respectivelubricant passage.

The first duct means may, if desired, extend alongside one only of saidraces, a lubricant conduit being provided through which lubricant maypass in contact with the said circumferential surface of the other race,said lubricant conduit communicating the said common scavenge means.

The invention also comprises a gas turbine engine provided with at leastone bearing assembly as set forth above.

The invention is illustrated, merely by way of example, in theaccompanying drawings, in which:

ICC

FIGURE 1 is a broken away section of part of a first embodiment of a gasturbine engine provided with bearing assemblies according to the presentinvention,

FIGURE 2 is a broken away section taken on the line 2- 2 of FIGURE 1,

FIGURE 3 is a section taken on the line 3-3 of FIGURE 1,'

FIGURE 4 is a view looking in the direction of the arrow 4 of FIGURE l,and

FIGURE 5 is a broken away section of part ofV a second embodiment of agas turbine engine provided with bearing assemblies according to thepresent invention.

Referring first to FIGURES 1-4 of the drawings, a gas turbine engine isprovided with a shaft 10 on which are mounted a high pressure compressorand a high pressure turbine (not shown). Concentrically mounted andnested Vwithin the shaft 10 is a shaft 11 on which are mounted a lowpressure compressor and a low pressure turbine (not shown).

The shaft 10, adjacent its rear end, is mounted concentrically within aninner race 12 of a thrust bearing 13. The bearing 13, which constitutesthe main thrust bearing of the engine, has ball bearings 14 which are inrolling contact with the inner race 12 and with an outer race 15 whichis mounted concentrically about the inner race 12. The outer race 15 ismounted within two annular members 16, 17 which are secured to eachother and to fixed structure 20.

A source of lubricant, diagrammatically shown at 19, Supplies lubricantto a lubricant pipe 21 which is mounted concentrically within the shaft11. Between the shafts 10, 11 there is a space 22 which, in operation,is centrifugally supplied with lubricant from the lubricant pipe 21 byway of radially extending lubricant passages 23.

Mounted within the shaft 10 is a sleeve 24 which bounds the space 22 andwhich is recessed to form a plurality of angularly spaced apart pockets25. Each of the pockets 25 communicates with a drillng 2,6 and is shapedto direct lubricant centrifugally into the respective drillng 26. Eachdrillng 26 communicates with a lubricant passage 27 which leads to themid region of an axially extending groove 30 in the innercircumferential surface 31 of the inner race 12. The outer ends of eachgroove 30 communicate by way of drllings 32 with annular chambers 33, 34which are respectively disposed immediately upstream and downstream ofthe bearing 13.

It will be appreciated that the lubricant flow through the grooves 30will serve to cool the inner race 12 by taking away heat which has beenconducted thereto through the shaft 10 and/or has been generated withinthe bearing.

The annular members 16, 17 have slotted portions 35, 36 respectivelywhich are respectively arranged to form boundary surfaces of the annularchambers 33, 34. The portions 35, 36 have slots 37 therein which serveto give a very fine metering control of a flow of lubricant therethroughfrom the drllings 32 to lubricant ducts 40 leading to the ball bearings14.

Lubricant which has been used in lubricating the ball bearings 14 passesthrough lubricant ducts 41 and through drllings 42, 43 in the annularmembers 16, 17 respectively to the annular chambers 33, 34 respectively.Lubricant which has thus been used in cooling and lubricating thebearing 13 passes to a scavenge passage 44. The latter communicatesdirectly with the annular chamber 34 and communicates with the annularchamber 33 by way of a passage 45.

The outer circumferential surface 46 of the outer race 15 has grooves 47therein which are supplied with lubricant from a lubricant conduit 50 byway of conduits 'D 51, 52, 53,54. The lubricant which has flowed throughthe grooves 47 and which has thus cooled the outer race passes throughdrillings 43a into the annular chamber 34 and thence to the scavengepassage 44.

Some of the lubricant from the lubricant conduit 50 may pass via aconduit 55 to the rear bearing (not shown) of the engine.

The shaft 11 is mounted Concentrically within a sleeve 56 whichconstitutes an inner race of inter-shaft ball shaft 11, the drillings 64communicating with the lubricant pipe 21 by means not shown. Thefrusto-conical member 63 is formed With scoops 65 (FIG. 4) which directa portion of the lubricant which passes onto the frusto-conical member63 from the drillings 64 to. the

ball bearings 57 and thence to the ball bearings 58, after which thelubricant is passed via drillings 74 in the shaft 10 to the annularchamber 33 and finally via the passage 45 to the scavenge passage 44.

Some of the lubricant which has passed through the drillings 64 iscentrifuged up the inner surface of the frusto-conical member 63 andflows through the holes 66 to an annular chamber 70 immediately upstreamof the ball bearings 57. This flow of lubricant passes from the annularchamber 70 and via drillings 71 to grooves 72 provided in the outercircumferential surface of the outer race 60. Lubricant which has flowedthrough the grooves 72, and which has thus cooled the outer race 60,passes axially through grooves 73 in the outer circumferential surfaceof the outer race 61 so as to cool the latter. This lubricant thenpasses into the annular chamber 33 by way of the drillings 74 in theshaft 10.

It will be seen that, where possible in practice, the lubricating oilsupply to each bearing is divided into two flows, one flow serving tolubricate the rolling elements of the bearing and the other flow servingto cool the inner or the outer race. It is preferable that the oil whichhas served as a cooling medium is not afterwards passed to the rollingelements to serve as a lubricant.

Referring now to FIGURE 5, a gas turbine engine is provided with ashaft'80 on which are mounted a high pressure compressor and a highpressure turbine (not shown). Concentrically mounted within the shaft 80is a shaft 81 on which are mounted a low pressure compressor and a lowpressure turbine (not shown);

The shaft 80, adjacent its rear end, is mounted concentrically within aninner race 82 of the main thrust bearing 83 of the engine. The bearing83 has ball bearngs 84 which are in rolling contact with the inner race82 and with an outer race 85 which is mounted concentrically about theinner race 82. The outer race 85 is secured to fixed structure 86.

Between the shafts 80, 81 there is a space 87 which, in operation, iscentrifugally supplied with lubricant from the interior of the shaft 81by way of radially extending lubricant passages 90 in the shaft 81.

Mounted within the shaft 80 is an annular member 91 which extends intothe space 87 and which is provided with a plurality of angularly spacedapart pockets 92.V Some of the pockets 92 communicate with a drilling 93into which the lubricant is centrifuged, theremaining pocketseommnnicating with a drilling 93a; Each drilling 93 communicates with alubricant passage 94. The lubricant passage 94 leads via drillings inthe shaft 80 to the mid region of an axially extending groove 95provided in the inner circumferential surface 96 of the inner race 82.The outer ends of each groove :95 communicate with annular chambers 100,101 which are respectively disposed immediately upstream and downstreamof the bearing 83.

It will -be appreciated that the lubricant flow through the grooves willserve to cool the inner race 82.

Some of the grooves 95 communicate with passages 102 in the inner race82, which open to annular chambers 97 defined by Shoulders 98. Lubricantducts 99 leading to the ball bearings 84 communicate with chambers 97and, thus, lubricant supplied to the passages 102 effect lubrication ofthe ball bearings 84. After the lubricant has effected the lubricationof the ball bearings 84, `it passes into the annular chambers 100,101.Lu-bricant which has thus been used in cooling and lubricating thebearing 83 `passes from the annular chambers 100, 101, to

a scavenge passage (not shown).

The outer circumferential surface 106 of the outer race 85 has grooves107 therein which are suppliedwith lubricant from a lubricant conduit110 by way of conduits 111, 112. The lubricant which has flowed throughthe grooves 87 and which has thus cooled the outer race 85 passes intothe annular chamber 101, and thence to the said scavenge passage.

Some of the lubricant from the lubricant conduit 110l may pass via aconduit 113 .to the rear bearing (not shown) of the engine.

The shaft 81 is mounted concentrically within a sleeve 114 whichconstitutes an inner race of inter-shaft ball bearings 115,`` 116. Thelatter have outer races 117,

118 respectively which .areimounted within a sleeve mem-` ber 120 whichis itself mounted within the shaft 80.

Lubricant from the interior of the shaft 81 maypass centrifugally, viaradially extending passages .121 in the` shaft 81, toan annular chamber122 within the sleeve member 120.

Some of the lubricant in the chamber 122 flows therefrom along afrusto-conical surface provided on the sleeve member 120 and through thebearing `115, so as to lubricate the latter. A proportion of thelubricant which flows along the said frusto-conical surface .passesthrough 'drillings 120a, provided in the said frusto-conical surface, toan annular chamber 12411.

The lubricant from the chamber 124aflows successively through grooves124, 125 ,provided in the outer circumferential surfaces of the outerraces 117, 118 respectively, so as to cool the latter, and then flowsvia drillings 123 and the chamber 100 to the said scavenge passage.

The bearing 116 is lubricated by lubricant from the pockets 92 whichcommunicate with drillings 93a, which lubricant is picked-up by aninwardly directed lip 126 provided on the cage member of the bearing116. After lubricating the bearing 116, the lubricant passes throughapertures 11811 and then through the drillings 123 and the chamber 100to the said scavenge passage.

Instead of providing the inner race 82 with the passages 102 forsupplying the lubricant to the balls 84 these passages may be dispensedwith and `replaced by passages 102a which communicate directly with theballs 84. This ensures that the lubricant which passes to the balls 84through the passages 102a has not received heat by cooling the innerrace 82.

We claim;

1. A bearing assembly comprising a first member, 'an

outer race which is mounted in `the first member, an inner.

said circumferential surface of the other race, second duct means,independent of at least one of said first duct means and said lubricantconduit, through which 'lubricant passes to the rolling elements toeffect lubrication thereof, a common source of lubricant, means forsupplying said first and second duct means with lubricant from saidcommon source of lubricant, and common scavenge means to which passeslubricant which has flowed through said first and second duct means andsaid lubricant conduit.

2. A bearing assembly as claimed in claim 1 in which said second ductmeans s independent of both said first duct means and said lubricantconduit whereby lubricant passing to the rolling elements to effectlnbrication thereof has not received heat as a coolant.

3. A lbearing assembly as claimed in claim 1 including at least onechamber into which lubricant passes from said first duct means, and afiow metering device` carried in said Chamber for metering the amount oflubricant passing to said rolling elements from said second duct means.

4. A bearing assembly .as claimed in claim 3 in which said fiow meteringdevice comprises a slotted member carried by the outer race.

5. A bearing assembly as claimed in claim 1 in which said second membercomprises a hollow rotatable shaft References Cited by the ExaminerUNITED STATES PATENTS 2,911,267 11/1959 Small 308-187 FOREIGN PATENTS1,093,768 11/ 1954 France.

644,930 10/ 1950 Great Britain. 764,860 1/ 1957 Great Britain. 781,0858/1957 Great Britain. 255,481 10/ 1927 Italy.

DAVID I. WILLIAMOWSKY, Primary Examin'er.

FRANK SUSKO, Examner.

